The present invention relates generally to the removal of sulfides from a process stream. More specifically, the present invention provides a method for determining the concentration of sulfides in a process stream.
Sulfides are generated in many aspects of the oil production and refinery industry. Sulfides can be generated in the oil fields where oil is collected as well as at the refinery wherein the oil is processed.
Due to the health hazards associated with the exposure to sulfides, it is important to remove sulfides from process streams in the oil field. Additionally, sulfides can also cause metal fatigue in crude units, and therefore must be removed; sulfides can cause hydrogen blistering in oil refineries.
Although methods do exist for removing sulfides from such process streams, these systems do not function entirely satisfactorily. Examples of sulfide scavengers include compounds chosen from a class of chemicals referred to as "aminals." These sulfide scavengers include bis-morpholinyl methane and N,N,N',N'-tetra alkyl diamino methane.
Although these sulfide scavengers provide compositions that can remove sulfides from a process stream, an issue arises as how to determine how much scavenger to use. Of course, if a sufficient amount of sulfide scavenger is not used, sulfide will remain in the process stream. On the other hand, if excessive amounts of sulfide scavenger are used, costs are unnecessarily increased and potential processing problems can result from the excess scavenger.
One method for the on-line detection of sulfide involves a system that employs the use of lead acetate paper. The lead acetate reacts with the sulfide and creates lead sulfide. A device is employed that determines the concentration of lead sulfide that is formed. This system is extremely expensive, with a cost of more than $50,000.00.
Additional methods for determining sulfide concentration include the use of near infrared detection. Additionally, sulfur specific chromatography is sometimes used. However, there are also disadvantages inherent with these systems. Houston Atlas, a Baker Hughes company, provides instrumentation that utilizes the lead acetate detection method. Additionally, sulfur specific chromatography is provided by Houston Atlas.